Brinsea all the way for me :yiipchick
I know they are more expensive but they are well worth it. I have the octagon 20 advance EX with humidity pump and love it. It really is a set leave incubator. Holds temp and humidity well pump takes all the worry out of humidity incubation. Can't praise it enough.
Circulated air gives a more even temperature around your eggs in the incubator. Rather than the still air that can cause the incubator to have hot and cold spots in various places which would cause the eggs to have abnormal development.